A fine structure, which is produced by processing silicon, has been widely used in the field of micro electro mechanical systems (MEMS) and in a functional device of an electric machine. More specifically, a fine structure is used in a liquid discharge head configured to discharge liquid, for example. A liquid discharge head that discharges liquid is used in an inkjet recording head used in an inkjet recording method for discharging an ink on a recording medium to record an image.
An ink jet recording head includes a substrate, on which an energy generation device configured to generate energy utilized for discharging liquid is provided, and a discharge port configured to discharge an ink supplied from a liquid supply port provided on the substrate.
U.S. Pat. No. 6,679,587 discusses the following method for manufacturing an inkjet recording head like this. In this conventional method, at first, a mask having a plurality of openings is laminated between a first silicon substrate and a second silicon substrate. Then, the first silicon substrate is etched to the second silicon substrate, and a first through hole provided through the first silicon substrate is formed. Thus, the plurality of openings of the mask is exposed.
Furthermore, the etching is continued to execute etching on the second silicon substrate by utilizing the exposed mask. Then second through holes corresponding to the plurality of openings are formed. In the above-described manner, supply ports provided through the first and the second silicon substrates are formed.
However, in etching the first silicon substrate, the etching speed in the direction of the thickness of the substrate tends to differ in different regions of the surface of a silicon substrate. Accordingly, the second through hole formed on a region on which etching has been executed at a high speed may be formed in a shape wider than a pre-determined shape toward the surface of the silicon substrate, compared with the shape of other second through holes. As a result, a desired liquid supply characteristic may not be achieved due to unevenness of the sizes of the second through holes.